| 摘要 |
PURPOSE:To improve the precision of transfer of a pattern by detecting relative positional variation between a mask holder and a stage generated by vibrations by taking the difference section of outputs from a laser interferometer and compensating the position of beam exposure. CONSTITUTION:Laser beams emitted from lasers 15, 16 are reflected by mirrors 11, 12, and reflected by half-mirrors 13, 14 again and enter photoreceptors 17, 18, and the wave number of the beats of laser beams reaching from positional counters 19, 20 is counted and the position X1 of a mask 4 and the position X2 of a wafer 1 are detected. Frequency multipliers 21, 22 receive outputs from said each laser interferometer and generate higher harmonics of N times as high as observed waves, these outputs enter a difference counter 23, and the relative positional variation sections of the positions X1 and X2 are detected by the counter 23. Outputs from the counter 23 are converted into analog quantities by a D/A converter 28 through a multiplier 24 and an adder 26, and transmitted over a deflecting coil 10 through an amplifier 29, and beams are deflected only by the quanty of said relative positional variation sections and compensated. |
